That card looks like combination of AHCI HBA, and two SATA port multipliers. So in theory that it should work on FreeBSD, since all required functionality probably in place. But that is only in theory. In practice SATA port multipliers significantly complicate I/O operation and error recovery. So I would not bet on reliability of that combination. Performance is also questionable there -- even not looking on PCIe x2 connector, simultaneous access to disks connected to the same port multiplier requires advanced functionality from HBA, and I am not sure that chip used there supports it.
I would probably not put such device into critical production, but I would be quite interested to read any review of such device under FreeBSD. I could even buy it just for fun if it would be sold in nearby shop.
